1. Field of the Invention
The invention relates to a signal processing technology, and particularly to an apparatus and a system for correcting touch signal and a method thereof.
2. Description of Related Art
With rapid advancement of technology and improvement of processing technology, various smart electronic products such as electronic products with a touch screen have become one of the most common portable equipments nowadays. The touch screen can be generally categorized into a resistive type, a capacitive type and an optical type, and the optical type touch screen can be generally categorized into a reflective type and a shield type.
FIG. 1(a) is a schematic diagram of a shielded type optical touch screen. FIG. 1(b) is a schematic diagram of an ideal original signal received by a camera module at upper-left corner in FIG. 1(a). A x-axis in FIG. 1(b) represents a pixel position, and a y-axis represents a signal intensity (e.g., grayscale brightness).
FIG. 2(a) and FIG. 2(b) are schematic diagrams of a covered region generated by the shielded type optical touch screen. As shown in FIG. 2(a), when one single finger F1 of a user touches the screen, the original signal is covered so as to generate the covered region which is a region pointed by an arrow 210 in FIG. 2(b). Accordingly, a mathematical algorithm can be utilized to further detect the pixel position of the covered region, so that a position of a touch point can be calculated.
FIG. 3(a) and FIG. 3(b) are schematic diagrams of the covered region influenced by an overexposure and generated by the shielded type optical touch screen.
As shown in FIG. 3(a), when one single finger F2 of the user touches the screen on a region closed to the camera module, optical effects such as brightness being too strong or diffraction may occur, which results in enhancing the signal intensity originally in the covered region thereby generating two covered regions (refers to two regions respectively pointed by arrows 310 and 320 in FIG. 3(b)). The overexposure may influence a result of analyzing the position of the touch point, such that errors or misjudgments may occur when the optical touch screen analyzing a signal distribution of FIG. 3(b).